Should every extra peak be called oxidation?

No. An unnamed peak stays unnamed. Oxidation is recorded only when the laboratory file uses that description.

Does a matching main mass rule out oxidized material?

No. The main ion and minor species are separate lines. Absence of an oxidation line means the report did not state one.

Glossary · 2026-09-24

Oxidized peptide impurity, laboratory note

Oxidation of a sensitive side chain, methionine included, can show up as an extra chromatographic peak or as a shifted ion. It is one possible member of an impurity profile. It is not a peak you may label on your own. If the Certificate of Analysis names an oxidized species, copy that name and the mass it cites. If it does not, leave the line blank.

A purity percentage does not say that oxidation was measured. Read the mass spectrum and the chromatogram that the file actually contains. Background on the two methods is in how peptide purity is measured. Research-use only.

Frequently asked questions

Should every extra peak be called oxidation?: No. An unnamed peak stays unnamed. Oxidation is recorded only when the laboratory file uses that description.
Does a matching main mass rule out oxidized material?: No. The main ion and minor species are separate lines. Absence of an oxidation line means the report did not state one.

Research-use only. BlueNex Labs does not provide medical or veterinary advice. Confirm your institution’s policies before purchase.